Oxygen administration



Sept. 11, 1951 McKEE 2,567,225

OXYGEN ADMINISTRATION 6 Sheets-Sheet 1 Filed April 14, 1944 INVENTOR.

Elva/lee Sept. 11, 1951 cKEE 2,567,225

OXYGEN ADMINISTRATION Filed April 14, 1944 6 Sheets-Sheet 2 1& J54 J56 Jfifilfl & J57 :1 J57 Jfi1 J73 -12? IN V EN TOR.

Sept. 11, 1951 c E 2,567,225

OXYGEN ADMINISTRATION Filed April 14, 1944 6 Sheets-Sheet :5

IN V EN TOR.

gerifl lyckee Sept. 1 l, 1951 A. E. M KEE OXYGEN ADMINISTRATION Filed April 14, 1944 6 Sheets-Sheet 4 u'UM Sept. 1 1, 1951 A. E. MQKEE OXYGEN ADMINISTRATION 6 Sheejs-Sheet 5 Filed A rii 14, 1944 $1 LAN Sept. 11, 1951 McKEE 2,567,225

OXYGEN ADMINISTRATION Filed April 14, 1944 6 Sheets-Sheet 6 War/ 11 Modem)? Wes/sf Patented Sept. 11, 1951 UNITED STATES PATENT OFFICE OXYGEN ADMINISTRATION Albert E. McKee, Chicago, Ill. Application April 14. 1944, Serial No. 530,968

rhythmic cycles independent of the conscious demand of the user, thereby having the general operating characteristics of a resuscitator. Reference is also made to my copending application Serial No. 537,803, filed May 29, 1944, which discloses related subject matter.

My present invention represents an improvement in several respects over the previously disclosed invention, notwithstanding the fact that some of the same general features and principles are involved. My present invention, however, provides for operation at continuous positive pressure, so that exhalation takes place against a positive back pressure, instead of through a restricted orifice to atmosphere, but additionally it provides for operation with intermittent oxygen pressure, either on demand orautomatically, in-

halation taking place while oxygen is being delivered under pressure, but exhalation taking place, when oxyyen pressure is discontinued, through a restricted orifice to atmosphere. The

oxygen is delivered on demand, substantially at ambient pressure, in which case the apparatus operates as a simple demand regulator; or at pressures above ambient pressure, in which event, the apparatus operates as a demand positive pressure regulator. My present invention also provides improved structural, control and operating characteristics. Such characteristics as well as other specific objects and features of the invention will be apparent from the specification which follows below.

The drawings disclose one embodiment of the invention adapted for use in aircraft. The invention is capable of modification and embodiment in other forms following the same general features. I

In the drawings:

Fig. 1 is a composite view partly in section and partly in elevation and also partly broken away, showing an oxygen administering mask, an expiratory valve and a regulator, in the general 2 positions which they may occupy during actual operation;

Fig. 2 is an elevational view of the regulator showing a dial used to indicate an adjustment thereof;

Fig. 3 is an elevational view of a portion of the expiratory valve, the figure comprising a sectional view taken on. the line 3-3 of Fig. 4. looking in the direction of the arrows;

Fig. 4 is a vertical sectional view taken through the expiratory valve, the section being slightly irregular and taken on the line 4-4 of Fig. 1;

Fig. 5 is a transverse plan sectional view taken on the line 5-5 of Fig. 4, looking in the direction of the arrows;

Fig. 6 is a fragmentary sectional view taken on the line 8-6 of Fig. 5. The figure may also be considered taken on the section line 6-6 of Fig. 4 and reference may be made to the section lines 6-6 on Figs. 4 and 5 for comparison and'for a better understanding of the relationship of the parts comprising Fig. 6;

Fig. 7 is an isometric view of the regulatorhous ing stripped of all of its parts except a portion of the expiratory valve control line;

Fig. 8 is a plan sectional view taken on the line 8-8 of Fig. 9, looking in the direction of the arrows, the figure comprising in essence a 'plan view with the diaphragm and some additional parts removed to show the construction of a double toggle arrangement which is not clearly brought out in other figures;

Fig. 9 is a transverse sectional view (a vertical section if taken on the line 9-9 of Fig. 2, as it might be) taken substantially along the line 9-9 of Fig. 8 with some of the parts being shown in elevation;

Fig. 10 is an enlarged fragmentary sectional view taken on the line lfl-lli of Fig. 8, looking in the direction of the arrows;

Fig. 11 is an enlarged fragmentary sectional view taken on the line li-il of Fig. 8;

Fig. 12 is anenlarged sectional view taken on the line l2-l2 of Fig. 8, looking in the direction of the arrows. The section may also be viewed as being taken along the line l2-l2 of Fig. 2;

Fig. 13 is a graph showing the relationship of pressure and time in a breathing cycle when the device is operated on the simple demand principle and in which the subject is at rest and the respiration substantially normal;

Fig. 14 is a view similar to that of Fig. 13, except that the two curves show, respectively, the subject engaged in moderate work and in excessive work;

Fig. shows a series of curves relating pressure to time in which the equipment is being operated automatically, generally in accordance with resuscitation procedure; and

Fig. 16 is a series of curves showing various breathing cycles, with various adjustments of the apparatus, each, however, involving the use of pressure and initiation of the cycle on demand of the subject.

Before proceeding with the detailed description of the invention as illustratedin the drawings, I wish to point out that for convenience of illustration and to save space, Figs. 7 to 12, inclusive, are placed in different relative positions than the corresponding parts of Figs. 1 and 2, but that, generally, conventions have been followed in the relationship of Figs. 8 to 12, inclusive, to each other. In order to clarify the relationship of the parts, in certain instances section lines have been indicated in more than one figure. Neither the expiratory valve nor regulator depends for its operation on being placed in any particular position and while, for convenience, some of the parts maybe thought of as comprisingv top or bottom, functionally the terms top or bottom should not be considered as of any significance.

Looking first at Fig. 1, I illustrate a face mask A connected by a tube to an expiratory valve B.-

A regulator C is connected to the expiratory valve B also by a tube, as will be described. The parts here occupy the relative positions which they may occupy when used for the administering of oxygen to personnel in combat airplanes. It will be noted that a fast operating connection is made between the tube leading to the face mask and the expiratory valve. Thus the pilot of an airplane or other user may have his own individual face mask, and the remaining portion of the equipment may be made available at his station in the airplane. The regulator C may, for example, be attached at one side at a sufficient level so that the control mechanism thereon can be seen and operatedby the user. The

expiratory valve B may be similarly mounted but,

preferably, it occupies a position relatively close to the mask. It may, for example, be secured to the clothing of the user by means of a heavy clip at some place on the chest. My invention provides for unusual flexibility in the arrangement and positioning of the parts thereof. I wish to remind those skilled in the art that the apparatus need not be separated into separate units of the character illustrated, and also that the expression expiratory valve and regulator are for identification and description only. The em bodiment of the invention in the particular form shown and described should not prevent a full understanding of the essential operations which the apparatus is meant to perform.

For convenience, I shall first describe the regulator C as appearing generall in Figs. 1 and 2 and in greater detail in Figs. 7 to 12, inclusive. This device is adapted to receive oxygen under pressure from a supply oxygen delivery pipe l6 and deliver it to the user rhythmically and in the amounts required. The regulator comprises a housing H which also acts as the main frame or support for apparatus contained therein, with a boss l8 for connecting the oxygen delivery pipe "5 to the housing, and a boss l9 through which a low pressure oxygen delivery tube is connected to the housing. One side of the housing is covered by a plate 2| having integral mounting lugs 2| used for securing the regulator in a desired position. The opposite side of the housing has secured thereto a housing cap 22 which also acts as a support for a portion of the apparatus comprising the regulator. A clampin ring 23 is disposeclbetween the housing cap 22 and the housing l1 and clamps a diaphragm 24 is position to close off entirely one side of the housing. The plate 2|, diaphragm 24 and a portion of the annular sides of the housing I! together define a large chamber 26 which, through the boss l3, communicates with an oxygen outlet tube 21 held in position by an attaching nut 28. Supply oxygen entering the regulator from pipe l6 passes through a passageway 29 into a high pressure chamber 3|. The high pressure chamber 3| is formed-in part by an annulus 32 (see Fig. 7) and an annulus offset 33, the surfaces of which are engaged by plate 2| so as to close the chamber 3| from atmosphere, portions of the annulus 32 and offset 33 serving to separate chamber 3| from chamber 26. Oxygen is adapted to be delivered from the high pressure chamber 3| for expansion into the chamber 26 through passageways provided for the purpose; and special valves and control mechanism are provided for controlling the movement of oxygen through such passage ways. For convenience, I shall employ the terms supply oxygen and expanded oxygen" to identify, respectively, the oxygen delivered to the regulator C, and the oxygen delivered by mechanism comprising the regulator C to and beyond the chamber 26.

The essential control of oxygen delivery is by means of the diaphragm 24, and mechanism including an overcenter toggle switch operated in part thereby. A stem 34 extends through the center of the diaphragm and is threaded on one side to receive a nut 36 (see' Fig. 12), a flange being provided on the side of the diaphragm opposite to the nut, and a pair of enlarged washers 31 being clamped between the flange and nut 35 same, is a compression spring 38, the upper end of which spring extends into a lowerannular, recess of a compression controlling member 39 and is held in place by suitable means such as cotter pins 4| or the like. Oxygen pressure within the chamber 26 moves the diaphragm against the compression of spring 38 when such spring is in contact with the diaphragm so that the amount of oxygen pressure required to move the diaphragm against the force of spring 38 is determined by the position of the compression controlling member 33. This determines the peak pressure in the chamber 26, so that the compression spring 38 has the function of a peak oxygen pressure controlling spring.

To control the position of the compression controlling member 39, I provide an eccentric 42, carried on a shaft 43. The eccentric 42 engages in a side recess of the compression controlling member 39, so that by. rotating shaft 43, the compression controlling member 39 is adapted to have its position (vertically looking at Fig. 12) controlled in a boss 44 on the housing cap 22. The shaft 43 is journalled in a plug 46 threaded in a reenforced aperture in the boss 44. A hub 41, integral with a handle 48, is secured to the projecting end of shaft 43 and pinned thereto.

between its extremes of movement. The extremes of movement are defined by stops 53', said stops comprising projecting ends of a stop plate 53 supported on the indicator plate 49. The stops 53' extend to a position at thesides of the nut and beneath the indicator plate 49 as appears in Figs. 1 and 2.

Within the center of the compression controlling member 39 is a tubular guide member 54 functioning partly as a guide for said compression controlling member and also as a guide for the diaphragm stem 34.. Tubular guide member 54 is threaded in the upper end of the boss 44 and its lower end is bored to receive the upper end of stem 34. A diaphragm return spring 56 in the guide member 54 has a spring follower 51 at the lower end thereof, the said follower being shaped to receive the upper conical'tip of the diaphragm stem 34, so that the parts can center themselves and the compression of the diaphragm return spring 56 can be applied to the end of the stem 94 without any tendency toward canting or tilting. The upper end of diaphragm spring 56 bears against an enlarged portion of a spring compressing plunger 58 vertically reciprocable in a plug 59 screwed into the upper end of tubular guide member 54. A return spring control cap 6| is secured to the upper end of the plunger 58 and a cap retaining spring 62 is disposed between the lower surface of the cap, which also acts as a housing for the spring, and the upper end of plug 59. Pins'63 carried by the plug 59 extend into slots 64 provided in the control cap 6|, the said slots 64 being so arranged that the control cap 6| may be held in either of two positions by spring 62. This positions the plunger 58 in such a manner as to cause greater or lesser compression of the diaphragm return spring 58 for a purpose which will later be explained.

Beneath the diaphragm 24, and partially within the chamber 26, is disposed the oxygen control valve equipment actuated in part by an overcenter type of toggle switch controlled by the position of the diaphragm. This diaphragm controlled toggle actuates a main oxygen control valve through the interposition of a relay valve actuated in turn by a relay toggle mechanism. In reading the explanation which follows, this general relationship should be borne in mind.

Surrounding that portion of the diaphragm stem 34 immediately below the diaphragm 24 is a toggle bracket 66 to which toggle arms 61 and 68 are pivoted, as shown particularly in Figs. 8 and 12. Toggle springs 69 are tensioned between pins 1| and 12 extending through the toggle arms 61 and 68, respectively. Arm 68 has a ball shaped terminus extending into a recess in a positioning bracket 13 carried by a projection 14 from the housing |1. Arm 61 has a bifurcated end 16 guided in a slot in a bracket 11 carried by a projection 18 from the housing l1. The toggle switch comprising toggle bracket 66, toggle arms 61 and 68 and toggle springs 69 actuates a relay toggle and a relay valve, as previously mentioned, and the assembly comprising such relay valve and relay toggle will now be described.

Near the end of that portion of the chamber 8| defined by the annulus offset 33 is a relay valve 18. the stem of which is disposed in a valve stem guide 8| mounted in an opening 82 (see Fig. 7) extending between the chambers 26 and 3|. The valve stem guide 8| has an enlarged head portion 83 (see Figs. 18 and 11) engaging the web surrounding the opening 82, and the other end of the valve stem guide 8| is threaded to receive a.

nut 84. The valve stem guide and nut 84 are provided with valve seats 88 and 85, respectively, and the material around the seats is cut away to provide enlarged passageways between such seats and thevalve stem 19. Between theoifset 89 (the opposite side to that seen in Fig. 7) and the nut 84, is disposed a relay toggle bracket 86,- the nut 84, therefore, serving not only to hold the valve stem guide in proper position but also to support the relay toggle bracket 86. A relay toggle arm 81 is pivoted at 88, intermediate its ends, to the relay toggle bracket 86. Springs 89 are tensioned between an upstanding portion of the relay toggle bracket 86 and a transverse portion 9| of the relay toggle arm 81. One end 81' of the relay toggle arm 81 is disposed in operable engagement within the bifurcated end 16 of the toggle arm 61 and the other end of the relay toggle arm 81 is adapted to engage a valve head 92 of the valve 19. A valve head 93 is disposed at the opposite end of the valve 19, and the contiguous portion of the valve stem guide 8| and nut 84, in each instance, is finished to form a seat for valve faces of the valve heads 92 and 98. An understanding of vthe function of the valve 19 and the manner of operation of the main and relay toggles must await a description of the structure of the main valve, the expansion valve, and the several ports and passageways functionally associated therewith.

The details of the main valve are shown particularly in Figs. 9 and 10, but reference should also be had to the remaining figures, particularly Figs. '7 and 8, for a full understanding of tire relation of the main valve to other parts of the regulator. The annulus 32 is provided with a central opening 94 (Fig. '7) in which is disposed a main valve stem guide 96 (Fig. 10). A main valve stem 91 has a main valve 98 secured to one end thereof and a head 99 at the other end comprising an upper valve. The valve stem guide 96 has an upper flange portion 96' through which suitable machine screws or other fastening means extend to support the main valve stem guide in position, and also to form a seal for the upper valve 99. A main valve seat member |8I is secured in position in the opening 94 so as to form a seat for the main valve 98. The valve stem guide 96 and main valve seat member I8I are spaced from each other to form a chamber I88, and the main valve seat member is recessed to form a passageway I82 around the valve stem whereby, when the main valve is opened, to place the chamber 8| in communication with chamber I88 and a passageway I83, one end of which communicates with chamber I88.

The opposite side of the annulus to that seen in full in Fig. 1 is provided with a cap I84 which functions as a retainer for a main valve diaphragm I86 (see Figs. 9 and 10). The center of the diaphragm I86 substantially coincides with the axis of valve stem 91. A diaphragm load bearing member I81, carried at the center of the main valve diaphragm, is adapted to engage the end of valve stem 91 whereby, in a manner later to be described, to force the main valve 98 from its seat.

secured over the slot I08 between the opening 82 passageway I in communication with the high pressure oxygen chamber 3I. The cap I04 is provided with a small angular passageway II3 aligned with the passageway I09, and, the diaphragm being provided with an opening at this point, the passageway I09 is placed in communication with a main valve expansion chamber II4 between the diaphragm I08 and the cap I04.

In addition to controllingsome of the parts of the expiratory valve B '(as will be later ex- -plained),the main function of the valve mechanism heretofore'described is to deliver oxygen from the chamber 3| to the chamber 26 through a, controlled expansion orifice. This is done through an expansion valve associated with the diaphragm stem 34 disposed substantially centrally of the housing I1, and integral with the annulus 32 is an annular expansion valve housing H6. The expansion valve housing II6 has an inserted expansion valve seat I I! in which a valve H8 is reciprocable, being retained on the bottom end of stem 34 by a nut H9. The expansion valve seat insert and tubular guide member 54 are vertically aligned so that the diaphragm stem 34 can be freely vertically reciprocable in both members without side strain, and without cramping the diaphragm 24. The passageway I03 terminates in an enlarged portion I03 extending part way around the inner surface of the expansion valve housing H6. The valve seat II! is provided with a plurality of radial openings I2I, placed 120 degrees apart, communicating with an annular expansion orifice I'22. The annular expansion orifice I22, it will be seen by an inspection of Fig. 12, is formed between an upper portion of the expansion valve I I8 of restricted cross section and an upper portion (above the radial openings I2I) of the valve seat III made slightly larger than the remaining portion thereof. Both the valve H8 and expansion valve seat I II are finished with sharp shoulders and the valve IIB fits snugly within the valve seat III at all portions thereof except at the annular expansion orifice I22.

It will be recalled that the function of the apparatus of my present invention is to deliver oxygen at a controlled peak pressure on demand of the user (on either the simple demand principle, or the demand positive pressure principle), oxygen delivery being discontinued when the peak pressure is reached, and the user permitted to exhale against a restricted orifice; to provide for automatic operation on the resuscitator principle; and also to provide for continuous positive pressure of oxygen on demand of the user with expiration against a fixed positive back pressure. These several methods of operation are required to be capable of regulation in accordance with other requirements, for example, requirements resulting from a change in ambient pressure and capable of either manual or automatic control by aneroids, solenoids, and the like. Before further describing and explaining the operation of-the regulator C, I wish to explain the construction of the expiratory valve B, it being understood that the terms regulator'- and expiratory valve are employed for identification and to facilitate description rather than in any rigid sense to mean that the parts of the apparatus are necessarily separated, constructed and/or operated in the identical manner shown. I

The expiratory valveB comprises a six sided housing I23 containing a main chamber I24. A boss I26 is shaped to receive an oxygen delivery tube I21, the other end of the oxygen delivery tube being connected to the regulator outlet tube 21. Expanded oxygen is, therefore, delivered to the chamber I24 through passageway I2-I in the boss I26. Opposite boss I26 is a boss I23 in which a tube I3I is threaded, the tube I3I being shaped to receive a coupling member of a suitable type carried by a tube I32 extending to the face mask A. The length of tube I32 may vary. It may be sectioned, orvarious adjustments may be made to control its length as will be explained. The tube I3I comprises an expiratory valve expanded oxygen outlet tube for the delivery of expanded oxygen through the flexible tube I32 to the mask; and, since breathing takes place through the expiratory valve, the tubes I3I and I32 also comprise exhalation tubes during the exhalation portion of the breathing cycle. It is preferred that the connection between the flexible tube I32 and the tube I3I be quickly made and quickly detachable while at the same time preventing loss of oxygen at the connection. Devices generally similar to that indicated in the drawing are known and may be used for the purpose.

One of the functions of the expiratory valve B is to close to atmosphere the oxygen delivery line running from the regulator C to the mask at the time oxygen is being delivered to the user and to open the tube l32 to atmosphere to permit exhalation when oxygen delivery has'been discontinued. The expiratory valve B is constructed to provide an exhalation orifice of a restricted and controlled type, in part, and as to some of its characteristics, under the control of the user but predominantly controlled by the regulator C. The portion of the expiratory valve B providing the restricted exhalation orifice will first be described; and then I shall explain the manner in which operation of the regulator C controls operation of the expiratory valve.

Threaded in an opening on thehousing I23 is a valve seat member I33 shaped to provide a seat I34 just within the chamber I24. supported at the centerof the valve seatmember I33 by radial arms I38 is a boss I31, andthis boss I31 carries the stem of a flutter valve I38 formed of semi-soft rubber or the like and bearing against a regular exterior portion of'the'valve seat member I33. An adjustable exhalator valve cover I33 is threaded on the exterior of valve seat member I33 and is provided with a semi-circular exhalator valve opening I 4| (see Fig. 3). The exhalator valve opening is adapted to be closed by semi-circular exhalator adjustment valve I42,

an integral shaft I43 of which extends through the side wall of the exhalator valve cover I33 and has a regulator handle I44 pinned thereto. The regulator handle I44 is apertured to receive 9 l a spring I46 which is placed under compression and bears against the outside surface of the exhalator valve cover I39 and holds the adjustment valve I42 against the smooth inside face surrounding the exhalator valve opening I4 I. A dial plate I41, secured in a recess on the outside surface of the exhalator valve cover I39, and a pointer I44, integral with the regulator handle, extends partly over the dial plate I41 so as to indicate the adjustment of the exhalator adjustment valve I42. v

The flutter valve and exhalator adjustment valve are auxiliary to the main valve for closi or opening the chamber I24 to atmosphere. The main valve comprises a valve I48 secured on a stem I49 reciprocable in a valve stem guide II The valve stem guide I5I is held in a web portion I52 of the housing I23 by a nut I53, a suitable gasket or washer being provided as indicated. A diaphragm I54 has the end of the valve stem I49 secured to its center and is held against a shoulder within a boss I56 by a diaphragm retaining nut I51. A cover nut I58 closes a diaphragm chamber I59 within the boss I56, a gasket I6I or other suitable packing being provided to prevent leakage from or to diaphragm chamber I59. A

' spring I62 normally holds the assembly comprising the valve I48, stem I49 and diaphragm I54 in the position shown in Fig. 4, with the valve I48 spaced from the seat I34. This spring I62 has a central looped section extending around a pin I63, projecting from the inner wall of the housing I23. One end of the spring I62 engages the inside wall of the boss I 26 and" the other end engages against a camoperating pin I64, engaging in a tapped radial hole in the valve stem I49. It will be noted that'valve stem guide I5I is provided with a slotted recess I66 (see particularly Fig. 5) extending to the outer surface of the stem I49. The end of the spring I62 extends into this slot and the cam operating pin I64 is also reciprocable in the slot in a manner and for a purpose to be described.

.The assembly comprising the valve stem guide I49, valve I48 and diaphragm I54 is held by the spring I62 in a position to maintain the expiratory valve I48 open, but is moved in a direction to cause the valve I 48 to engage the seat I34 when gas pressure within the diaphragm chamber I59 causes the diaphragm to be expanded. To understand the manner in which gas under pressure is delivered to the diaphragm chamber I59, reference will be made to parts of the expiratory valve B and also to parts of the regulator C.

Extending through the material comprising the boss I26 is a tube I 61 comprising a part of a high pressure control line leading from the oxygen source to diaphragm chamber I59. The tube I61 is suitably introduced during the production of the casting comprising the housing I 23 and boss I26, and is so arranged that one tip thereof extends out to receive a small flexible tube I68 (see Fig. 1) disposed within the larger tube I21 and the other end of which is in communication with the diaphragm chamber I59. The tube I68 leads to the regulator C and oxygen under pressure is delivered thereto at the same time that oxygen I'll is threaded into that end of the passageway I69 which leads to chamber 26 (see Fig. 7). A flexible connecting tube I12, however, extends from the projecting end of tube I1I to a tube I13 extending through a portion of the metal comprising the boss I9. The tube I13 communicates with an annular recess I14 formed on the end of boss I9 (see Figs. '7 and 9). The regulator outlet tube 21 is also provided with an end annular recess I16 and a tube I11 extending through the metal comprising the said regulator outlet tube 21, communicates with the annular recess I16. An apertured gasket I15, as shown, provides a communication between the annular recesses I14 and I16. The lower end of the flexible tube I68 is secured to the connecting tube I11. Thus through the connections shown and described, the expiratory valve control line is made to interconnect the chamber 3I (through the passageway I03) and the diaphragm chamber I59. When oxygen under pressure is delivered from the chamber 3| to the passageway I03, therefore, the said pressure is communicated immediately to the diaphragm chamber I59. It will be noted that the annular recesses I14 and I16 align themselves (through the apertured gasket I15) when the regulator expanded oxygen outlet tube 21 is applied in position, so that regardless of the manner in which the regulator outlet tube 21 may be rotated with respect to the boss I9, the connecting tube I13 will always be placed in communication with the connecting tube I11, and the expiratory valve control line will always be connected.

In order to provide for additional exhalation capacity, and to secure other functions which will be described, I have also provided in the expiratory valve B, an additional valve, which, for identification, I shall term an auxiliary valve. The

operation of the auxiliary valve will be described later, but now I shall try to make clear the structural features thereof.

Secured in a threaded aperture on one face of the expiratory valve housing I23 is an auxiliary valve'seat member I18,-a sealing gasket I19 being provided between an annular flange portion of the auxiliary valve seat member I18 and a contiguous portion of the housing. A portion of as to form, with the contiguous portion of the housing I23, a smooth exterior surface, as shown particularly in Fig. 1. An auxiliary valve guide I84 is disposed between the auxiliary valve cover I83 and the valve seat member I18, the valve guide having a plurality of spaced legs I86 so disposed as to guide the auxiliary valve but permitting oxygen or other gas passing between the valve I82 and its seat to escape to the interior of the auxiliary valve seat cover I83. A plurality of edge openings I81 are provided in the cover I83 to permit the escaping gas to exhaust to atmosphere.

The auxiliary valve I82 is held against its seat by a spring I88, one end of which is secured to the center of the auxiliary valve I82 and the other end of which is secured to theend of an auxiliary valve stem I89. The auxiliary valve stem I89 is reciprocally supported in an offset portion I9I of the valve stem guide I5I. The opposite end of the auxiliary valve stem guide I89 is secured to the center of diaphragm I92 secured in one face of the housing I26 by an auxiliary valve diaphragm cover I93, the exterior of which is threaded to engage in internal threads provided on the housing I23. The auxiliary valve diaphragm cover I93 is apertured to permit ambient atmospheric pressures to be eifective against the exterior face of diaphragm I92. Extending parallel with the auxiliary valve stem I69 is a cam shaft I94 to which is secured a cam I96. The cam shaft I94 and cam I96 may be integral, but the cam I96 comprises essentially a disc disposed eccentrically on the shaft I94. A cam arm I91 has a pair of integral fingers I96 and I99, disposed adjacent the valve stem guide II but on opposite sides of the cam operating pin I64 secured in the valve stem I49. The center open portion of the cam arm between the fingers I96 and I99 is enlarged so as to permit free movement of the cam arm without having it come in contact with the auxiliary valve stem I69. A set screw 292 extends through the cam arm I91 and engages the cam shaft I94 so that movement of the cam arm I91 caused by the cam operating pin I64 striking the fingers I96 and I99 will cause the cam shaft I94 to rock, and rocking of the cam shaft I94 will have the efiect of either disengaging the cam I96 from the auxiliary valve stem I69 or engaging the said valve stem for a purpose and in a manner to be described.

Before describing the various controls, features, and the manner of operating in accordance with different principles or requirements, I shall first describe merely the functioning of the apparatus comprising the regulator C and valve B. In describing the operation, the adjustment of spring 96 will be disregarded, and it will be assumed that the parts are in the position which they occupy when oxygen is first being delivered through the chamber 26 up through the outlet tube 21 and eventually to the mask, that is to say, the toggle switch has just operated to open the main valve,

but oxygen has not entered sufiiciently to build up a pressure beyond chamber 3|. The oxygen is delivered through the pipe I6 from a suitable source of supply and at suitable pressure controlled by means known in the art and with which this invention is not concerned. With the parts in the position shown in the drawings oxygen passes through the passageway 29 into the chamber 3|, through the passageway I92 into passageway I99, and out through the annular expansion orifice I22, and expands into the large chamber 26. From here, the expanded oxygen is delivered through the tube system and the expiratory valve device B into the mask A. At the same time that expanded oxygen is delivered to the chamber 26, oxygen under pressure is also delivered through the passageway I69 and through the expiratory valve control line including the tubes I12, I13, I11, I66, and I61 into the diaphragm chamber I69. The oxygen entering the chamber I69 actuates the diaphragm I64 to move the diaphragm valve assembly, including valve stem I49, thus to engage the valve I46 against its seat I94. This prevents loss of oxygen through the expiratory valve, and oxygen thereupon expands into the large chamber 26 and fiows through the oxygen delivery line I21, through chamber I24, through tube I92 and into the mask A. Oxygen is received by the regulator C at a relatively high pressure, at least of the order of eight pounds per square inch and up to twenty-five pounds per square inch or even more depending upon the specific construction of the apparatus. Before the oxygen starts to expand into the chamber 26 the pressure in this chamber is relatively low, for example, on the order of ambient pressure. As soon as the pressure starts to build up slightly in chamber 26, however, the diaphragm 24 is lifted slightly, carrying with it the expansion valve II6. Raising the expansion valve II6 has the eifect of partially closing the expansion orifice I22, since the shoulder on the expansion valve will then be brought up past the radial openings HI, and the greater diameter portion thereof will then define the expansion orifice. This forms a smaller cross-section annular orifice, and the rate at which oxygen is permitted to enter the chamber 26 is greatly reduced. The user of the device continues to inhale so that oxygen enters the chamber 26 through the expansion orifice at only a slightly greater rate than that at which it is taken into the lungs of the user. It should be remembered that the oxygen is in motion and cannot be said to be at a fixed definite pressure during this portion of the cycle. There is a gradual slight rise in pressure, however, until the user has ceased to inhale and at this point the oxygen pressure rises sufiiciently to over-balance the total force tending to keep the diaphragm in a lower position, including that of springs 69. These forces may involve atmosphere pressure above the diaphragm, the spring pressure of compression spring 36 (if in engagement with the diaphragm), the tension of toggle springs 69, and the pressure of spring 66.

When a pressure has been built up in the chamber 26 sufficient to overcome the forces at any one time resisting the upward movement of the diaphragm 24, the toggle bracket 66 is carried upwardly a sufilcient distance so that the center line of springs 69 is below the pivot points between the arms 61 and 66 and the toggle bracket. The toggle acts like an overcenter switch mechanism and when the toggle bracket 66 has been raised a sufiicient distance to cause the springs 69 to snap the arms about their pivots in the opposite direction, the arms are carried to the position indicated in dotted lines in Fig. 12. When this movement of the toggle arms occurs, the bifurcated end 16 of the arm 61 rotates the relay toggle arm 61 about its pivot 66 (Fig. 11) and disengages the tail portion of the arm 61 from the head 92 of the valve 19. It will be noted that there is considerable play betweenthe end 61' of the relay toggle arm 61 and the bifurcations comprising the bifurcated end 16 of the main toggle arm 61. Thus incipient movement of the toggle arm 61 prior to the time that the toggle arm snaps over center from one extreme position to the other is not sufiicient to actuate the arm 61; but when the arm 61 is moved, it also can move with a snap or overcenter action, and its end 61' can advance further than it is carried by the arm 61. The full and dotted line positions of Fig. 12 will illustrate this feature. The construction is such that both toggles have independent snap movement notwithstanding the fact that one is actuated by the other.

Still disregarding the principle on which the apparatus is being operated, let us examine the normal effect of actuation of the toggle switch mechanism on attainment of th peak pressure as described hereinabove. When the head 92 of the valve 19 is released, the pressure in chamber 6| being greater than the pressure in chamber 26, the valve 19 is snapped upwardly (when in the position shown in Figs. 10 and 11) and the 13 valve face of the head 93 engages the seat 80 while the valve face of the head 92 is released from its .seat 85. I have found that oxygen pressure alone is suflicient to cause a return movement of the valve I9 but those skilled in the art will understand that I may utilize any suitable force to cause a return movement such as a spring if deemed necessary. When valve 93 is closed to cut off flow of oxygen to the main valve diaphragm chamber II4, high pressure oxygen bleeds from this chamber past valve 92, as will be explained. The stem of the relay valve 19 may be formed loose enough in the valve stem guide 8i to permitsuch bleeding action; but to clarify the action obtained, I show a relatively small opening 208 in the valve stem guide extending from the valve seat 85 to the passageway 2. When the valve I9 has been operated, therefore, the high pressure in the diaphragm expansion chamber.

I I4 is released through passageways H3, I09, I08,

I I2 and 266 to the relatively lower pressure chamber 20. The pressure below the diaphragm I06 is at all times substantially static due to a relatively small passageway 201 running from the chamber below th diaphragm into the chamber 26 and also due to the factthat when main valve 98 is open, valve 99 is closed, so that such oxygen as might otherwise bleed past the stem 91 will be prevented from entering the chamber below the diaphragm. When pressure is releas 1d above the diaphragm II4, therefore, th main valve comprising the stem 91 and valve heads 9B and 99 is caused to flip upwardly, again due to the relatively greater pressure in the chamber 3| than above the valve 99. In the case of this main valve I have also found in actual practice that oxygen pressure alone in general is adequate to actuate the valve; but that separate valve returning force such as a spring or other equivalent of as pressure may be employed. As soon as the valve head 5-8 engages its seat, the passageway I02 is taken out of communication with passageway 3| and passageway I03 is still open to chamber 26 through the annular expansion orifice I22 (see Fig. 12). Passageway I69 with which the expiratory valve control line is connected also is connected and disconnected from the high pressure chamber 3|. This permits an immediate lowering of pressure in the diaphragm chamber I59 and unseating of valve I48 from valve seat I34. The entire expanded oxygen delivery system beyond the main valve 90, including chamber 26, the mask A and interconnecting tubes I21 and I32, may, therefore, be opened to atmospheric pressure by the opening of the expiratory valve- For the moment, I shall not discuss the details of the expiratory cycle, it being sufficient for the present to point out merely the parts and operations involved. The actuation of the toggle switch and main and relay valves, as described, takes place so rapidly as to be. almost instantaneous, notwithstanding the fact that there is a flow of oxygen until a peak pressure is attained, and a shutting off of oxygen during the expiratory portion of the cycle after such pressure is attained. The inspiration portion of the cycle is initiated when the several forces which are involved at any one time (depending upon principle of'operation) move the diaphragm and toggle mechanism to a position to open the relay and main valves. I shall discuss this operation later in connection with a description of the several methods of operation which may be utilized.

In order to understand details of operation,

demand regulator, the spring 38 is entirely out" 14 those skilled in the art should have an explanation of some of the terminology used herein. By a simple demand regulator I mean a regulator in which the oxygen is delivered on demand of the user at substantially ambient pressure, or at a pressure only sufliciently higher than ambient to cause the oxygen to flow to the mask; and wherein oxygen delivery is discontinued when the user ceases to inhale, and exhalation takes place to' atmosphere through a restricted orifice. By the expression demand positive pressure regulator I mean a regulator wherein oxygen is delivered when demanded by the user, but flows or builds up to a pressure above ambient pressures. "I employ the term positive pressure generally herein to mean a pressure above ambient, and the term negative to mean a pressure below ambient.' Thus the simple demand regulator differs from a demand positive pressure regulator, principally in the peak oxygen pressure attained'at the end of the inhalation portion of the cycle. By the term peak pressure I mean the relative pressure at which oxygen delivery to chamber 26 is discontinued. The apparatus of my present invention may be operated automatically-that is to say on the principle of the resuscitator. When 's'o operated oxygen is delivered until the peak pressure is reached, as determined by adjustment, regardless of the demand of the user, and both oxygen delivery and discontinuance thereof are independent of the demand of th user. Exhale-'- tion takes place to atmosphere through a restricted orifice. The apparatus of my invention may also be operated as a continuous positive pressure regulator. By this I mean that the oxygen is delivered under pressure and continues to flow so long as the user inhales the same, but that exhalation takes place against a positive back pressure.

When the apparatus is operated as a simple of contact with the diaphragm, and the peak pressure at the end of the inhalation cycle is at a minimum. When the flow of oxygen has been discontinued and the valve I48 opened, the user exhales against a restricted orifice determined by the adjustment of valve I42.

The pressure within the chamber 26 relatively quickly returns to ambient pressure from the relatively slight positive pressure which had been attained therein and which was suflicient to move the diaphragm 24 to its uppermost position. There is a slight loading of the diaphragm by the spring 56, but the spring 58 alone is not sufficient to overcome the tension of springs 69 when the mechanism is adjusted for operation as a simple demand regulator. Because of this relation of springs 58 and 89, the toggle mechanism will be maintained in a position to close valve 98 throughout the exhalation portion of the cycle and regardless of lowering of pressure within the chamber 26. In other words, if the user of the apparatus should, for any reason, completely exhale and then hold his breath, the toggle switch would not operate, even though the expiratory valve continued open. When the user of the apparatus demands oxygen, however, by

the act of starting to inhale, he causes a slight When the before mentioned slight negative pressure is created in chamber 28, the added force applied to the diaphragm in a direction to bring it to its lowermost position is sufllcient with the spring 56 to overcome the force of springs 69 and the arms 61 and 68 are brought past dead center, withthe result that the toggle switch snaps to the position shown in full lines in Fig. 12. This action of the toggle switch opens valve 83 which, in turn, admits oxygen under pressure to chamber I I4, opens the main valve 98 and also admits oxygen to the expiratory valve control line, all as previously described, to cause a flow of expanded oxygen to and through chamber 28 and ultimately to the mask A while at the same time forcing valve I48 against the seat I14.

At times it is desirable to operate the apparatus as a demand positive pressure regulator wherein the peak pressure developed in chamber 26 is definitely above ambient. There may be various reasons for operating the apparatus as a demand positive pressure regulator, but I shall illustrate by reference to altitude. It is the pressure of oxygen within the lungs, that is to say, the so-called alveolar oxygen pressure, which determines whether or not oxygen will be absorbed and, if it will, the rate of absorption. As an illustration, the oxygen pressure at sea level is about 159 mm., this being due to the fact that only 21% of the atmospheric pressure of 760 mm. at sea level comprises pressure of oxygen. As altitude is gained, the oxygen pressure is decreased and this may be compensated for by admixing oxygen with air up to approximately 30,000 feet, at which altitude it is generally customary to start the use of pure oxygen. It has been found, as a practical proposition, that above about 38,000 to 40,000 feet pure oxygen at atmospheric pressure is insufficient. At 40,000 feet,

for example, the total pressure of the atmosphere is such that, even if pure oxygen were delivered, the actual pressure of oxygen would be much less than at sea level. If the pure oxygen is delivered under positive pressure, then the total pressure of oxygen may be brought up to approximately that at sea level (or definitely higher if desired). While the apparatus of my present invention may be constructed in various ways, I have found that the spring 38 may be kept out of contact with the diaphragm entirely below about 30,000 feet. Above 30,000 feet, and as altitude is gained, the spring 38 may be gradually lowered in order to increase the peak pressure in the chamber 26.

A high altitude is not essential for the apparatus to operate as a demand positive pressure regulator, but operation in a rarefied atmosphere affords at least one instance where the apparatus is required to deliver oxygen at positive pressure as it is being operated in response to demand of the user.

To understand the functioning of the apparatus when it is operated as a demand positive pressure regulator, let it be assumed that spring 38 is adjusted to some intermediate position at which its lowermost coil is engaged by the diaphragm 24 before the diaphragm 24 reaches its uppermost position. The apparatus will then operate in the following manner:

When the relay and main valves have been opened, oxygen is admitted through the expansion orifice I22 to expansion chamber 26 and at the same time to the expiratory valve regulator line to force valve I48 against seat I34. When oxygen first enters the chamber 24. the expansion orifice has its maximum cross sectional area and there is a quick surge of oxygen toward the mask of the user. As soon as the chamber 26 starts to become filled with oxygen, the first or immediate demands of the user being satisfied, the diaphragm 24 and associated parts are raised slightly to decrease the cross sectional area of the expansion orifice I22. Generally speaking, the first movement of the diaphragm will take it up into engagement with the spring 38. There will then be a continued flow of oxygen until a peak pressure is reached, determined by several factors, including the total oxygen intake of the.

user, time, the 'action of spring 56 and the adjustment of spring 38. When the peak pressure is reached, the toggle switch mechanism operates to cut off further flow of oxygen and to permit opening of the expiratory valve. The user has received oxygen under a pressure greater than ambient pressure, but at the end of the inhalation cycle he exhales, not against the positive pressure developed in the mask A, but to atmosphere through a restricted orifice, the area of which is determined by the adjustment of valve I42. When he has exhaled, the inhalation portion of the cycle again is not initiated until the user demands oxygen. When he makes his first movement to inhale, a slight negative pressure is created, exactly in the same manner as when the apparatus operates as a simple demand regulator, and the inhalationportion of the cycle is resumed as previously described.

In the operation as described hereinabove, it was assumed in each instance that the apparatus was being operated on the demand principle. In order to operate the device as a resuscitator, the control cap BI is moved to its lowermost position so as to increase the compression of spring 56. It will be recalled that spring 56 normally is not quite strong enough to overcome springs 69 and that until the user demands oxygen by starting to inhale and thereby creates a slight negative pressure in chamber 26, the toggle switch will not operate and the inhalation portion of the breathing cycle will not be initiated. When, however, spring 56 is further compressed by the lowering of plunger 58, it then has sufficient power to overcome the force of springs 69 and return the diaphragm, 'even though a negative pressure is not created in the chamber 26 by the user starting to inhale. When the pressure of chamber 26 is lowered to approximately ambient pressure, therefore, the diaphragm is returned by spring 56 and the inhalation portion of the cycle is initiated automatically. Conversely, when the peak pressure is attained, oxygen delivery ceases and the expiratory valve is opened. The muscle tonus of the user. or patient, will cause a substantial portion of the lung contents to be expelled when the expiratory valve is opened; while the delivery of oxygen under some pressure (determined by adjustment of spring 38 plus the compression of spring 56) will assure delivery of enough oxygen to maintain life. A user of the apparatus may himself adjust it for automatic operation, or it may be adjusted by another. For example, if a member of a bomber crew should be wounded and loses consciousness. a fellow member can quickly adjust his oxygen apparatus to automatic operation.

As was previously noted, the user of the apparatus .exhales against a restricted orifice, the cross sectional area of which is determined by the position of the adjustment valve I42. Genr l v a kins. the orifice MI is restricted at will be developed in the chamber I24.

high elevations and increased at lower elevations, but circumstances may dictate an adjustment of the valve I42 other than merely in response to change in elevation. The dial I41 may, therefore, be calibrated in thousands of feet elevation, or the equivalent thereof, or in other values, depending upon the results required at a given time. Generally speaking, it is desirable to have a high average or mean pressure of oxygen during as much of the breathing cycle as possible, it having been established thatthe absorption of oxygen by the blood is dependent not only upon alveolar pressure but also upon the average amount of time that that pressure exists. The apparatus of my present invention can be operated so that the inhalation portion of the cycle is relatively short and the lungs are filled rather quickly with oxygen or so that the expiratory cycle is relatively longand the exhalation curve formed by plotting pressure against time is relatively fiat on top. The apparatus can be adjusted to various breathing cycles as expressed by curves showing inspiration and expiration against time.

In order to permit rapid release of spent oxygen by the user of the apparatus, the auxiliary valve I 82 is provided and I would like now to describe the manner in which this particular valve functions. It is used to permit escape of oxygen at a definite pressure above the peak pressure which The manner in which this is accomplished is as follows: When there is no pressure in chamber I24 and diaphragm I92 is in the position shown in Figs. 4 and 6, valve I82 will be held on its seat by spring I88 but only at a slight pressure. When the valve I48 is closed, however, and oxygen pressure is developed in chamber I24, a pressure is created on the inside surface of diaphragm I92 and there is a tendency to pull the auxiliary valve stem I89 in a direction to produce a greater tension in spring I88. Normally the cam I98 engages the surface of the auxiliar valve stem I89, however, with sufficient braking action to prevent the shaft from being moved in either direction. When the valve stem I49 is moved fully to the left (looking at Figs. 4 and 5) a suiiicient distance to engage the valve I48 against the seat I34, the cam operating pin I84 carried by the stem I49 strikes the finger I98 and rocks the entire assembly comprising the shaft I94, arm I91 and cam I98,

.to slightly disengage cam I98 from the surface of the auxiliary valve stem I89. The auxiliary valve stem I89 is now free to move in its guide and the pressure generated in chamber I24 will cause a corresponding flattening out of the auxiliary valve operating diaphragm I92. It will be recalled that the pressure developed in chamber I24 is determined by the adjustment of arm 48 controlling the position of spring 38 and generally will be in response to change in ambient pressure resulting from change in altitude when the device is used in aircraft. Assuming, for example, that the adjustment is sufficient to produce a gas pressure of 10 mm. of mercury, a pressure generally equivalent to 10 mm. of mercury will be applied against the inside surface of diaphragm I92 and a corresponding increased tension built up in spring I88. As long as the valve I48 is closed, the parts including the diaphragm I92, auxiliary valve stem I89 and spring I88 will remain in the position to which they have been moved by the increased pressure in chamber I24. As soon as valve stem I49 starts to move in a direction to open the valve I48, the cam operating scribed. It should be remembered that the position of the fingers I98 and I99 does not remain fixed and, therefore, the position at which they are engaged and disengaged by the cam operating pin I84 changes. The result of this automatic adjustment of the tension with which valve I82 engages its seat is that the user is always able to exhale against the auxiliary valve I82 by exerting a pressure through the act of exhaling which is a fixed slight value above the maximum pressure at any particular adjustment. If, at any time, therefore, the user wishes to exhale, he may do so. If the user of the apparatus expels the contents of his lungs in the manner permitted by the emergency valve arrangement, the shape of the breathing curve is entirely changed.

When the apparatus of my invention is used as a continuous positive pressure regulator, exhalation takes place against a fixed positive pressure or back pressure. This manner of operation may be brought about by entirely closing the'orifice I with the adjustment valve I42. When the expiratory valve is adjusted in this manner, then exhalation takes place through the emergency valve. only. The exhalation .takes place against a pressure determined by the adjustment of spring I88, but inhalation takes place more or less the same as previously described. The spring 38 being adjusted todetermine the peak pressure developed on inhalation, oxygen is delivered to chamber 28 and thence to the mask until the pressure in the chamber 28 reachesthesaidpeakpressure. Thereaching ofthis maximum pressure is determined by the amountof oxygen entering the chamber 28 and also by the amount of oxygen which the user takes into his lungs. When this pressure has been reached the switch comprising the toggle arms 81 and 88 is operated and the admission of further oxygen is discontinued exactly in accordance with the operations as previously described. The tension of spring I88 will also have been increased in proportion to the maximum pressure in chamber 28, and notwithstanding the fact that valve I48 may be entirely opened there will be no loss of oxygen from the chamber 28 because valve I42 has been closed as postulated, and valve I82 is still held to its seat at a pressure slightly above the pressure in chamber I24. By exhaling against the positive pressure in the chamber I24, tube I32 and mask A, the user of the apparatus can expel the contents of his lungs, the valve I82 being forced from itsseat sufficiently to pass substantially the volume of gas which the user of the apparatus has forced from his lungs. As soon now as the user discontinues exhalation and makes an effort to inhale, the pressure in the chamber 28 will be lowered sufiiciently to permit actuation again of the oxygen valves and the admission of a fresh supply of oxygen to the chamber 28 and thence to the mask. When the apparatus is used in this manner, it is necessary for the user either to exhale a large portion of the total gas content of the system (includ- I 19 fng his lungs) or to cause-considerable decrease of pressure on inhalation, inzorder to operate the togglemechanism and obtain a fresh supply of oxygen. There will never be a time when continuous negative pressure is required to obtain oxygen since as soon as oxygen starts to flow, it continues under pressure until the peak pressure is attained. Expedients for further loading the diaphragm to facilitateretum of oxygen fiow even when the pressure thereof at the end of exhalation remains relatively high may be employed. In the embodiment of the invention disclosed, the increased compression of spring 58 produced by manipulating-the plunger 58 is such an expedient.

There are several additional features of my invention which have not been fully discussed. Among such features are the ease with which the user of the apparatus may adjust himself thereto, this being due to the fact that, generally speaking, he is permitted to behave breathwise in approximately the same, way in which he would behave if he were breathing normally at sea level. If the user should, for any reason, cease to inhale after starting to inhale, a peak pressure can be built up quickly and further delivery of oxygen will be discontinued. If, at any time, during the breathing cycle, he should wish suddenly to expel substantially all of the lung contents dueto fright, for example, or because of sighing, or for any other reason,.the auxiliary valve I82 will be unseated with the result that the user is not dependent solely on the restricted orifice III. Even if the expiratory valve should be closed, the auxiliary valve can be oxygen firststarts to flow into chamber 26 causes a rapid delivery of oxygen to the mask A at the start of the inspiratory portion of the breathing cycle. If. the user of the apparatus breathes normally, the orifice I22 will be partly closed, and pressure will be built up relatively slowly,

giving the user of the'apparatus a normal amount of time to inhale. If after starting to inhale he should suddeny take a deep breath, or if'he should inhale large quantities of oxygen rapidly, as may occur if he is doing heavy work,'the orifice I22 will remain fully open or, if partially closed, will be opened to its maximum area toprovide quickly for the needed additional quantities, of oxygen caused by the excessive demand therefor. At no time, can the user of the apparatus develop a negative pressure by deep breathing after the slight initial negative pressure created at the beginning of the inspiratory portion of the breathing cycle when the apparatus is beingoperated as a simple demand regulator or canbe made any length desired and is removable forreplacement by alonger or shorter tube to control the amount of carbon dioxide which will be dispersed in the inhaled atmosphere. In hospital work, it is sometimes desired to control where the tube I32 connects therewith; or the tube I32 may be made relatively long if a large amount of carbon dioxide is desiredin the atmosphere as taken into the lungs. The apparatus of my present invention can be used to advantage for many types of treatment, for example, to provide a patient with a mixture of gases other than oxygen and nitrogen, such as a mixture of oxygen and helium for the purpose of combating certain types of asthmatic conditions. It should be clear that while the apparatus of my present invention is advantageous for supplying oxygen in sustaining amounts and pressures to aviators and the like-and the invention is particularly-adapted for such use in the embodiment shown in the drawingsmy invention has other utilities in the oxygen therapy and related fields.

It must not be assumed from the description of the manner in which the apparatus of my present invention may be operated, that it is required to be operated in any particular manner. Its big advantage is that it lends itself to any type of control or operation found desirable under various conditions, such as combat conditions in airplanes. I wish to point out, for example, that, generally speaking, the restricted expiratory orifice will have a smaller area at high elevations than at relatively lower elevations. Since as .a general rule it is more comfortable to exhale through some restriction than directly to low pressure atmosphere, the area of the orifice Ill will be controlled to suit the comfort of the user. It may be found that some advantage is obtained by utilizing an expiratory orifice of a size not favoring maximum comfort, in which event, by sacrificing the comfort of the user to some extent such additional advantage may be obtained. This general situation, as explained, with respect to the expiratory valve, may be true as to all adjustments including, for example, the peak pressure control. The apparatus of my present invention can be adjusted entirely by hand at the will of the operaconnected to the mask and the pilot starts to breath therethrough. A mixture of oxygen and vair i delivered under pressure through pipe I6 and the proportion of oxygen is gradually increasedby means known in the art, until at 30,000 feet pure oxygen is being delivered. From 10,000 to about 30,000 feet the device operates as a simple demand regulator. but with varying oxygen content in the incoming atmosphere. At a determined point above 30,000 feet (and at least by the time a 38,000 foot altitude is reached) -thepeak pressure is increased to cause the device to operate as a demand positive pressure regulator. The peak pressure is increased gradually as altitude isgained, and the pilot can safely rise to 50,000 feet or higher, if his equipment will 'take him there, and the apparatus supplies accurately the amount of carbon dioxide which the patient inhales and this may readily be done with the apparatus of my invention. It is ob- Y vious that the expiratory valve can be placed oxygen at sufiicient pressure to permit the pilot to do useful work at the elevation reached. The

pilot is not required at any time to exhale con tinuouslyagainst a positive back pressure, nor

there is an automatic compensation of oxygen pressure, so that he 'can entirely forget his oxygen equipment without danger of anoxemia. The pilot can himself adjust the device to operate as a resuscitator but, generally speaking, such adjustment is more apt to occur where there are a number of men in a crew and the adjustment is used by one to meet an emergency encountered by another.

The operation of the mechanism is, in part, illustrated by reference to curves such as shown in Figs. 13-16, inclusive. It should be understood with respect to all of these curves that none of them is intended to show oxygen fiow but only the relationship between pressure and time. Those skilled in the art will understand that it is possible to have a condition in which two curves showing the breathing cycle would be identical in every respect but in which the actual volume of oxygen flow would be. different.

The actual shape of the curves may vary but,

in general, they will have the features and salient configuration aspects illustrated in the drawings.

Referring now first to Fig. 13, the two curves there shown represent two breathing cycles in which the subject is at rest, in which the respiration is normal and in which the mechanism is adjusted to operate on the simple demand principle, that is to say, in which a slight inspiratory efi'ort on the part of the subject is required to initiate oxygen flow and in which the peak pressure at which-oxygen flow is discontinued is only slightly above ambient. The drawings show this peak pressure as one and one-half inches of water, low enough so that, for all practical purposes, the device is operating substantially at ambient pressure but high enough so' that positive operation of the valve mechanism is assured. In Fig. 13, the horizontal ordinate is marked with numerals to identify seconds while the vertical axis is marked with divisions to indicate pressure. It will be noted that zero pressure is indicated by a dotted line and, for convenience only, the pressure is marked on a line corresponding to minus two inches of water. In the curve, the numeral 2 I II identifies the point of slight negative pressure caused by the subject starting to inhale. At this point, the diaphragm 24 and associated parts are in the position shown in Fig. 12 and at the beginning of this period no oxygen is flowing. Just at the start of the period indicated by the portion of the curve 2), the diaphragm 24 is almost to its lowermost position, in other words, at a point almost low enough to operate the over-center mechanism comprising the toggle arms 61 and 68. When the slightly negative pressure is established, desirably corresponding to one-fourth of an inch of water, as indicated in the drawing, the toggle arms move to establish the position shown in full lines in Fig. 12, thereby opening valve 93, actuating diaphragm I06 and admitting oxygen from the high pressure chamber through the passageways provided to the now fully open expansion orifice I22. The oxygen then flows quickly and starts to build up a pressure in the mask through chamber 26. During this period, the subject is inhaling and, while there is a water, the diaphragm 24 is raised sufiiciently to tendency for the pressure to be compensated for by inhalation of oxygen, the fact that the expansion orifice provides for a quick surge of oxygen results in relatively rapid increase of pressure. This period is indicated by that portion of the curve marked with the numeral 2 I I. Those skilled in the art will understand that by modifying the proportions of the expansion orifice the line 2 could be made to rise more sharply or less sharply. During that part of the curve.

marked with numeral 2I2, the diaphragm 24 has risen partially and the expansion orifice I22.

has been decreased in cross section due to the fact that valve IIB has been raised to partially close the orifice I22. Thus, the pressure is per mitted to increase somewhat gradually notwith-- standing the fact that there is a decrease in oxygen intake. This part of the curve can also be influenced by modification in the shape and size of the orifice.

When the pressure reaches a peak M3, in this instance shown at one and one-half inches of cause the toggle mechanism to snap to the dotted line position of Fig. 12 and cut-off further flow of oxygen. At the same time, high pressure oxygen is delivered to the expiratory valve B through tube I11 and valve I48 is opened. The peak 2I3 is shown slightly fiat, indicating a brief period of unchanged pressure, this feature being a function of the design and is not influenced by the breathing habits of the subject. The line 2 indicates that exhalation is uniform, being controlled mainly by lung tissue recoil. The numeral 2I6 identifies the normal resting period between respirations shown as comprising slightly more than one-half minute but differing somewhat from subject to subject and from time to time. The length of this period is not influenced by design features.

In connection with the above, it should be pointed out that the cycle is initiated by the subject and will follow any rate of human respiration. In the drawings, a respiratory rate of approximately twelve cycles per minute is indicated. This is relatively slow and may, of course, vary but is not unusual when the oxygen intake is increased and the subject is at complete rest. The peak pressure of one and one-half inches may be varied but is close enough to or below the normal resting pulmonic recoil pressure of about one-half inch of water during resting respiration and, for this reason, will not cause respiratory fatigue and will only slightly, if at all, cause the subject to be conscious of his breathing. The period of negative pressure is so short and of such a minimum value that it is substantially efiortless and has very little eifect on producing respiratory fatigue and permits the patient to breathe essentially unconsciously. Normal inspiratory negativity measured at the nostril is .between approximately one-half inch and one inch of water so that the negative pressure indicated is substantially normal.

Those skilled in the art will understand that slight variations in the equipment, in adjustment of the mechanism and the like may introduce some slight variations in the curves. The portion 2 of the curve follows normal expiratory experience and assumes normal lung tissue recoil against substantially a normal ambient pressure; As already pointed out, the valve I 42 is controllable to reduce the expiratory orifice when ambient pressure substantially lower than sea level pressures areencountered. For this reason the shape of portion 2l4'of the curve may vary depending upon ambient pressure and/or the adjustment of the expiratory valve. The entire curve cycle can shape itself to normal expiratory experience, since it will naturally adjust itself to the subject's expiratory rate, the capacity on inhalation responds to the subject's ,needs and such incidents as coughing, signing, etc. are substantially as normal as in ordinary natural breathing. Clearly, also, the subject can converse without difilculty, due to this obvious and natural adaptability of the device.

Now referring to Fig. 14, two curves are shown indicated generally by the reference characters 2" and 2", the former illustrating a typical breathing cycle when the device is operated on the simple demand principle and the subject is performing a moderate amount of work; and the latter a breathing cycle under the same conditions except that the subject is engaged in the performance of excessive work. The two curves are, for convenience, placed in juxtaposition but it is understood that, normally, successive breathing cycles, having the pattern shown, would not occur in immediate succession but there would "24 nism and start oxygen flow, is substantially the same as in the two previously described conditions. When the oxygen stars to flow, the expansion valve is entirely open, but the lungs remove the major portion of oxygen because of the urgent demand therefor, the period of slight negativity is somewhat prolonged and the period of maximum lung filling, as indicated at 223, is decreased. Thereafter, the oxygen pressure builds up rapidly as shown by the line 228 to reach an initial peak 23L There is a dwell at this poin which is not under the control of or characteristic of the subject, but a function of the equip ment. The initial peak 23!, and dwell at such pressure, is, as in previously described conditions, at one and one-half inches of water. Due to the fact that the subject exhales rapidly when performing excessive work and also because of the increased amount of gas in his lungs, the regular expiratory orifice is inadequate and offers a resistance to exhalation. The accessory muscles and not merely lung tissue recoil play a part in exhalation under these circumstances, with the result that there is an increased intra-pulmonic be a number of cycles for transition'from the condition of moderate work to excessive work.

When the subject is working, more oxygen is consumed than when the subject is at rest. The

respiratory exchange in the latter case, the consumption of more oxygen (increased volume may modify the pressure curve only slightly), and more rapid or explosive exhalation.

In the case of moderate work, as shown by the curve 2", the incidence of trip negatively, as indicated at the point H9, is the same as when the subject is at rest. During the initial inhalation period 22l, the oxygen is flowing rapidly and as long as this period is sustained the oxy en continues to flow rapidly and the lungs continue to fill at an accelerated rate. Initially, the orifice I22 is entirely open but starts to partially close near the end of this period, hence decreases its cross sectional area and admits oxygen less rapidly. The closing occurs later than in the case of complete rest because of the rapid in- "halation of the subject. The lungs are filled at a of water as in the previous instance and in ac-' cordance with the conditions postulated. The period 224 remains substantially the same as in the resting state except that the accessory muscles may modify the curve slightly. The curve, however, may remain substantially the same but it is to be borne in mind that there will usually be a greater volume of exhalation than when the subject is at rest. The straight line 225 indicates the normal pause between cycles shown here relatively shorter and, for convenience connected to the curve showing a breathing cycle when excessive work is performed.

In the second curve, the period of negative pressure, as indicated at 221, to trip the mechais an abrupt pressure fall along the line 232 101- lowed by a gradual increase in expiration time along the line 233 to the end of the expiratory phase coinciding with the normal pause 234 between cycles. While the normal pause is determined by the characteristics of the subject, the

time thereof is, in general, shorter directly proportionally to the amount of work being performed.

Fig. 16 shows a series of breathing curves illustrating characteristic cycles when the peak pressure is increased substantially above ambient, in which oxygen fiow is initiated on demand of the subject and in which various conditions involving activity of the subject and adjustment of the apparatus are encountered. The chart comprising the figure is drawn on the same scale as the charts of Figs. 13 and 14 discussed hereinabove. For convenience, the several illustrative cycles are connected together but in actual operation there would necessarily be a gradual conversion from one set of conditions to the other.

The curves are repeated to show identical situations in each instance with, however, the peak pressure five inches of water in one case and fifteen inches of water in the other. Looking now first to the curves 236 and 231 showing, respectively, a peak of fifteen inches of water and five inches of water, the trip negativity remains the same as in previously postulated conditions and the period of initial active lung filling and gradual increase of pressure to the peak is substantially the same as in theother embodiments except that the actual pressure rise is greater. The peak pressure may be set at any reading from I the normal peak of one and one-half inches to the maximum which the subject can stand without injury under the conditions of operation, the maximum normally thought to be about sixteen to twenty inches of water. In this case, also, there is a slight period of unchanged pressure at the top indicated by the slight flattening out of the curve, the duration of which may vary slightly due to design of the equipment. In the 25 curves identified by the numerals 236 and 231, the subject is at rest and there is no appreciable expiratory resistance, that is to say, the valve I42 is substantially fully open so that exhalation is substantially directly to atmosphere. Exhalation is due to lung tissue recoil and the pressure drops relatively sharply and substantially in a straight line to the normal inspiratory pause shown by the horizontal line at zero pressure. In the next set of curves identified by the characters 238 and 239, the subject is at rest but exhales against an expiratory resistance caused by the partial closing of valve I42. The incidence of oxygen flow is substantially as described in previous embodiments and inhalation and development of the peak pressure follows the same patterns as in the curves 236 and 231. Due to the introduction of expiratory resistance, however, exhalation is prolonged and takes place at a varying rate so that the curve showing the expiratory phase of the cycle does not follow substantially a straight line as in the case illustrated by the curves 236 and 231. The exhalation curve 238a is characteristic of the introduction of only a relatively small amount of expiratory resistance, that is to say, in which the valvev I42 isclosed only slightly while the curve 238!) is characteristic of the exhalation portion of the cycle when still greater expiratory resistance is introduced by further closing of the valve. Corresponding conditions are shown by the curves 239a and 23312 at the lower pressure indicated. When the subject is resting and exhales through a partially closed orifice or other means providing for expiratory resistance, there is a normal pause at the beginning and end of each-cycle.

Curves 2 and 242 are typical of the breathing cycle when moderate work is being performed and there is no expiratory resistance. It will be seen that the curves follow the curves 236 and 231 fairly well with the exception that the period of rapid lung filling when the expansion valve I22 is at or near thefiood stage is increased. In other words, the conditions are comparable to those contrasted in the discussion of Figs. 13 and 14. The straight portion of the inspiratory portion of the cycle, in which the pressure is built up rapidly to the peak to which the apparatus is adjusted is the same as for the curves 236 and 231, but it should be borne in mind that these curves could have identical shape except that there would be greater oxygen flow due to the greater demand of the subject, since under the conditions discussed with respect to curves I and 242 the subject is exhaling without expiratory resistance, the expiratory portion of the cycle is substantially a straight line but, in any case, there is substantially a uniform rate of pressure loss to ambient pressure where there is a respiratory pause shown by the horizontal line.

The curves 243 and 244 represent conditions the same as the curves MI and 242 except that the expiratory valve is adjusted to introduce a resistance to exhalation. The portions 243a and 243b, as well as the portions 244a and 244b, illustrate the pressure changes on exhalation corresponding generally to those associated with the curves 238 and 239 but modified slightly due to the fact that there is somewhat more gas being expelled from the lungs due to the fact that a moderate amount of work is being performed.

The curves 246 and 241 illustrate a typical breathing cycle when the subject is performing an excessive amount of work and the expiratory valve is not set to introduce added resistance.

There is a greater demand for oxygen and lengthening out of the period of rapid oxygen intake at which the expansion valve is at or near flood stage but thereafter the pressure rise to the peak of fifteen inches and five inches of water, respectively, such as postulated, is rapid and follows substantially the pattern of the previously described cycles involving increased peak pressure. 'Exhalation during excessive work is such as to increase the intra-pulmonic pressure sharply with the result that there is a momentary sharp increase in pressure above the initial peak pressure followed by an opening of the valve I82 and a succeeding rapid loss of pressure along the lines 246a and 241a, respectively. Following the sharp drop in pressure, due to the opening and subsequent closing of the valve I82, there is a more gradual decrease in pressure indicated by the more gradual slope of the line identifying the expiratory phase. The pressure returns to zero or ambient pressure as in previously described embodiments and the respiratory pause is shorter.

The final set of curves of Fig. 16, 248 and 249, are typical of breathing cycles when excessive work is being performed and the expiratory valve is adjusted to increase expiratory resistance. The curves follow the outline of curves 246 and 241 up to the development of the peak pressure but thereafter there is a change due to the changed pattern of the expiratory phase. When the expiratory valve I42 is only partially closed, the expiratory portions of the curves follow the general outline as indicated by the lines 248a and 2490, respectively. It will be noted, that there is some flattening out of the maximum'peak and a gradual loss of pressure durin 'the beginning of exhalation due to the fact that the amount of gas which can pass through the expiratory valve during a given period is decreased. Some gas will escape through the valve I82, to be sure, but this valve is unseated only momentarily and immediately closes when the pressure has been reduced only slightly. The pressure curve on exhalation thereafter follows the general outline shown. When the expiratory valve is still further closed, the expiratory phase of the cycle is still further lengthened, as indicated by the curves 24% and 24%.

Reference may now be had to Fig. 15, showing typical breathing cycles involving varying conditions, each, however, assumin that the sub- I ject is not breathing voluntarily and the mechanism is adjusted to function automatically. This means that there is an additional loading of the diaphragm 24 by manipulation of control cap 6| (Fig. 12), that the toggle mechanism will function to initiate oxygen flow when the pressure in chamber 26 is still slightly above ambient pressure. The mechanism can be adjusted to trip and initiate oxygen flow at a positive pressure of onehalf inch of water. In the identical curves indicated by the references 25I, fiow of oxygen is started at one-half inch positive pressure, and

the period of lung filling and rising pulmonic pressure shown by the initial portion of the curves, coincide until a peak pressure, shown in these curves as corresponding to seven inches of the cycle, the expansion orifice I22 is fully open as in the condition on demand, and, dependingupon exact dimensioning of parts and conditions, including lung capacity of the subject, there may be some modification in the beginning portion of the curve. The actual pressure may not be a straight line from minimum to maximum points, but has been indicated as a straight line to show that the rise is gradual and substantially uniform, being due entirely to increased volume of gas introduced and is not modified by active voluntary inhalation on the part of the subject. In curves 252 and 253, the peak pressure has been increased to fifteen inches and eight inches, respectively. As indicated by the position of the apex showing the peak pressure, variations from curves 25l relate substantially only to the maximum pressure attained, but the shape of the curves otherwise follow that described in connection with curves 25L In the curves 254 and 256, the peak pressures are also adjusted to fifteen inches and eight inches, respectively, but introduction of expiratory resistance extends the period of exhalation, thereby slowing down the expiration time and causing a higher meanpressure to exist during a given cycle. The numerals 254a and 256a indicate characteristic shapes of the expiratory portion of the curve with the introduction of only a portion of the resistance permissible by the adjustment of the expiratory valve. The lines 2541) and 256b, respectively show the pressure-time relation when a still greater expiratory resistance is introduced.

What I claim as new and desire to protect by Letters Patent of the United States is:

1. In an oxygen administration system, of the character described, an expiratory valve mechanism, comprising a casing forming a valve seat, a valve engageable against said seat, a diaphragm responsive to pressure within the casing to force said valve against said seat, a second valve seat, a valve, spring means pulling said valve to its seat, and means responsive to pressure within the casing for loading said spring above the pressure effective against said diaphragm, whereby said last mentioned valve may be forced from its seat at a pressure slightly above the pressure closing the first mentioned valve.

2. In an oxygen administration system, a regulator including a casing forming a low pressure oxygen chamber and a high pressure oxygen chamber, a diaphragm having one side in con-' tact with said low pressure chamber, an overcenter switch operated by movement of said diaphragm, a control valve operated by said switch, a second diaphragm having a chamber on one side thereof, amain valve operated by said second diaphragm, a passageway leading from said high pressure chamber .to said diaphragm chamber, said passageway being opened by said control valve, 2. second passageway between said high pressure chamber and low pressure chamber controlled by the said main valve, the relationship of the parts being such that movement of the first mentioned diaphragm in response to a minimum and a maximum pressure will close or open said control valve and the second mentioned diaphragm will thereby close or open the said main valve to out off the flow of oxygen, or deliver oxygen to said low pressure chamber, a normally open expiratory valve, pressure responsive mechanism for closing the same, and a passageway leading from said main valve I 28 passageway to said mechanism for closing the expiratory valve when the oxygen is flowing from the said high pressure chamber to the said low pressure chamber.

'3. Oxygen regulating apparatus of the character described, including an oxygen delivery line, a mask in connection with said line, a diaphragm, one side of which is in communication with said line, a valve for controlling delivery of oxygen to said line, overcenter switch mechanism responsive to position of the diaphragm for operating said valve, means for loading said diaphragm just short of the point required to operate said switch mechanism to open said valve, whereby slight negative pressure in the said delivery line is adequate to operate said switch mechanism, open the valve and deliver oxygen to said line, additional spring loading means engageable by the diaphragm for controlling the peak pressure in the delivery line required to move the diaphragm to a position to operate the switch mechanism and open the said valve mechanism, an expiratory valve opening said mask to atmosphere, a valve closing the said opening but operating in response to attainment of a peak pressure in. the said delivery line to open said mask to atmosphere, and an auxiliary spring pressed expiratory valve in said line adapted to be forced from its seat to permit exhalation at a pressure above said peak pressure.

4. In an oxygen feeding system wherein oxygen is delivered to a mask on demand and discontinued on attainment of a peak pressure, an expiratory valve mechanism in communication with the said mask, an auxiliary release valve, a spring urging said release valve to its seat, a diaphragm subjected to pressure within the mask and a connection between said diaphragm and release valve, the construction and operation of said diaphragm and release valve being such that the said release valve may be forced from its seat by the development of a pressure within said mask only slightly above said peak pressure.

5. In an oxygen feeding system wherein oxygen is delivered to a mask on demand and discontinued on attainment of a peak pressure, an expiratory valve mechanism in communication with said mask, an auxiliary release valve, 8. spring urging said release valve to its seat, a diaphragm subjected to pressure within the mask and a connection between said diaphragm and release valve, the construction and operation of said diaphragm and release valve being such that-the said release valve may be forced from its seat by the development of a pressure within said mask only slightly above said peak pressure, said expiratory valve mechanism including an expiratory valve normally opened in response to development of said peak pressure, and means for retaining the loading of said release valve spring when said expiratory valve is opened.

6. In an oxygen feeding system wherein oxygen is delivered to a mask on demand and discontinued on attainment of a peak pressure, an expiratory valve mechanism in communication with said mask, an auxiliary release valve, a spring urging said release valve to its seat, a diaphragm subjected to pressure within the mask and, a connection between said diaphragm and release valve, the construction and operation of said diaphragm and release valve being such that the said release valve may be forced from 

